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Radiation Safety An overview of OSHA and UNI standards University of Northern Iowa Environmental Health & Safety Office Training Program
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Radiation Safety An overview of OSHA and UNI standards University of Northern Iowa Environmental Health & Safety Office Training Program
This training program was established to create a broader awareness for the safety of the University of Northern Iowa employees and their working environment. It is mandatory that all workers be trained and certified prior to the use of radioactive materials. This program is also to help employees determine the need for more advanced training.
Who should complete this training? • Any employee of the University of Northern Iowa who may be occupationally exposed to radioactive materials. • This includes ancillary personnel, such as clerical, housekeeping, or security, whose duties may require that they work in the vicinity of radioactive material.
Training Requirements Initial Training Required for anyone who has not been previously authorized to work with radioactive materials at the University of Northern Iowa. Annual Refresher Training Required every twelve months to continue authorization to use radioactive materials at the University of Northern Iowa.
Purpose of this Training Completion of this training course will fulfill The University of Northern Iowa’s initial radiation safety training requirement for those named as individual users on our current Academic Iowa Radioactive Materials License.
UNI’s Radiation License • The University of Northern Iowa’s Academic Iowa Radioactive Materials License is provided by the Iowa Department of Public Health. • Any action that jeopardizes this license, jeopardizes the permission of all individuals to use sources of ionizing radiation at UNI. Contact the RSO at 273-6234 to view other radiation notices, regulations, licenses, and license conditions.
Inspections & Audits Iowa Department of Public Health Inspections IDPH performs unannounced annual inspections to make sure that State regulations and University license conditions and policies are being met. Radiation Safety Officer Audits UNI’s RSO periodically audits radiation user compliance. Exposure rates and contamination levels are checked to ensure they are kept as low as is reasonably achievable.
Reporting Concerns or Violations You have the right to report any safety concerns or violations. • If you have a concern or suspect that a radiation safety violation has occurred please contact your supervisor. • If adequate corrective action is not taken, notify Megan Yasuda, UNI Radiation Safety Officer, at 273-6234. • If the violation is still not resolved, contact IDPH at 515-281-3478 or 515-281-3231. • IDPH regulations prohibit discrimination against individuals who report radiation safety concerns or violations.
Amending Authorized Use • File an amendment to UNI’s radiation license with IDPH whenever changes occur in an existing user’s authorization. • To maintain compliance, authorized users must file an amendment form with the Radiation Safety Officer (273-6234). • Examples of changes include: • Adding or deleting personnel • Changes in use areas • Changes in shipping or on-hand limits • Changes in radionuclide type, chemical form, and/or methodology Click here to access amendment forms
Topics Click on a link to go directly to that section. Radiation & Its Effects Minimizing Radioactive Exposure Radiation Laboratory Rules Warning Label & Sign Requirements Testing for Contamination Receiving Radioactive Materials Spill & Emergency Response Plan Proper Disposal of Radioactive Waste Radioactive Materials Records Contacts & Additional Information
Natural Sources of Radiation • Elements such as thorium, uranium, radium, RN-222, and K-40 are naturally occurring radioactive elements that can be found in our everyday lives. • These elements can be found in: • rocks, soil and building materials • food and water • Some sources are a result of ground nuclear testing, which is not naturally occurring.
Cosmic and atmospheric radiation originates from the sun, supernovas, and quasars. Earth’s atmosphere is very effective in shielding cosmic radiation, but variations in the density of the atmosphere can result in uneven distribution of protection. Cosmic and Atmospheric Radiation
Additional Sources of Radiation • Our bodies contain naturally occurring radioactive elements, such as potassium. • Some consumer products, such as luminous dial watches and smoke detectors, contain small amounts of radioactive material. • Cosmic radiation can be accumulated through one cross-country airplane trip. • Tobacco leaves absorb naturally occurring radioactive materials from the soil and fertilizers used to grow them. • Hospitalized individuals who undergo medical procedures are exposed to sources of ionizing radiation.
Ionizing Radiation • Ionizing radiation is produced by the natural decay of radioactive material. • Beta, gamma, and x-rays are forms of ionizing radiation that are often used in research. Beta, gamma, x-rays remove electrons from atoms (Ionization). Ions are created, which are more chemically reactive than neutral atoms. Ions can form compounds that might interfere with cell division and metabolism or cause chemical changes in tissue.
X-Rays & Gamma Rays • X-rays and gamma rays make up part of the electromagnetic spectrum. • They can travel forever until they hit an object and one of three reactions occurs: Scattering Transmission Absorption
X-Ray Production X-rays are produced when an atomic nucleus stabilizes itself by taking an electron from an electron cloud. Captured electron leaves a vacancy in the electron cloud. Electrons rearrange themselves to fill the vacancy. X-rays are emitted.
Gamma Ray Production Gamma rays are released when an atomic nucleus releases excess energy after a decay reaction. • Many beta emitters also emit gamma rays. • There are no pure gamma emitters.
Shielding X-Rays & Gamma Rays • Lead shielding will reduce the intensity of x-rays and gamma rays being emitted from a source of radiation. • To reduce exposure by a certain desired percent, lead shielding must be a certain thickness for each type of emitter. Remember: Lead shielding does not automatically reduce exposure by 100%.
Penetrating Radiation-X-Rays & Gamma Rays- • X-rays and gamma rays can penetrate the body and irradiate internal organs. • Exposure can result in external and internal doses. • Internal exposure can occur when rays are ingested, inhaled, or absorbed through the skin.
Beta Particles • Beta particles are excess electrons. • Beta particles are formed when an atom with one excess neutron transforms the neutron to a proton and ejects the extra electron. • Particles can be low or high energy emitters. • Low energy emitters can be shielded by cardboard. • High energy emitters need a more dense shielding material, such as Plexiglas.
Bremsstrahlung Radiation & Shielding • Bremsstrahlung radiation occurs when high energy beta emitters interact with high density materials, such as lead. • Bremsstrahlung conversion is minimal in plastic or acrylic shielding. • Shielding approximately 1 cm thick is adequate. • Avoid shielding less than 1 cm because it breaks and cracks easily.
Non-Penetrating Radiation-Beta Particles- • Can not penetrate the body to irradiate internal organs. • Can penetrate dead outer-layer of skin and result in damage to live skin cells. • Can cause damage to eye lenses. • Ingestion, inhalation, or absorption through the skin might result in internal exposure.
Radiation Absorbed Dose-RAD- • RAD is a unit of measurement used to describe the amount of energy transferred from a source of ionizing radiation to any material, including human tissue. • Use the abbreviation “rad/hr” when measuring an x-ray, gamma, or beta dose. As a unit of exposure, 1 rad means that each gram of air at 0° C and 1 atmosphere has absorbed 100 ergs of energy. As a unit of dose, 1 rad means that each gram of exposed tissue has abosorbed 100 ergs of energy.
Radiation Equivalent in Man-REM- • Different types of ionizing radiation cause differing degrees of biological effects even when the same level of energy is transferred (same number of ergs). • To create a universal measurement, the “rad” is multiplied by the specific quality factor for a type of ionizing radiation to determine the dose equivalent. • The rate at which an individual is exposed (i.e. an hour verses a lifetime) also influences the level of biological harm. • Use a dosimeter to measure a dose equivalent.
Biological EffectsExposure above permissible levels may result in: • Somatic Effects • Physical effects • May be immediate or delayed • Genetic Effects • Birth defects due to irradiation to reproductive cells before conception • Teratogenic Effects • Cancer or congenital malformation due to radiation exposure to fetus in utero
Biological Effects-Threshold- Threshold effects might occur if an individual receives a dose above the threshold level. • Acute Radiation Syndrome: large whole body dose in a short time • Effects occur at 100,000 mrem • Radiation-induced cataract formation • Acute effects occur at 200,000 mrem • Chronic effects occur at 800,000 mrem • Other thresholds • Severe skin injury occurs at 1,500,000 mrem • Teratongenic effects occur at 20,000 mrem
Biological Effects-Non-threshold- Non-threshold effects might occur from any amount of exposure to radiation. • Chance of effect occurrence is proportional to the received dose. • Severity of effects are not necessarily related to exposure level. • Chance effects include: • Cancer - estimated to be 5 deaths per 10,000 persons, whom each received 1,000 mrem • Genetic effects - not a likely result of occupational exposure
Units of Radioactivity Millicurie and Microcurie are units of activity that describe the rate of radioactive decay as a function of time. 1 curie Ci = 2.22 x 1012 dpm 1 millicurie mCi = 2.22 x 109 dpm 1 microcurie μCi = 2.22 x 106 dpm dpm = disintegration per minute
Radioactive Decay Equation Use this equation to determine the activity of radioactive material at any given time. A(t) = [A0] [e(-λt/T)] A(t) = number of radioactive atoms at a given time A0 = number of radioactive atoms at time zero (originally) e = base of natural log λ = a constant (0.693) t = number of days of decay T = half-life (in days) of the radioactive material of interest
Half-Life • Half-life tells how fast radioactive material decays. • It is the time required for one-half of the radioactive atoms in a sample to decay or disintegrate. • Half-life is measured in days. • It is used to tell how long radioactive material must be stored before it can be discarded as normal waste. At UNI, disposal cannot occur until 10 times the half-life has passed.
Minimize Exposure When working with radioactive material, remember to minimize your exposure at all possible times.
Measure Your Radiation Dose-Dosimeters- Use to measure the occupational dose equivalent from x-ray, gamma, and high energy beta emitters. Dosimeters cannot detect radiation from low energy beta emitters.
Avoid Inaccurate Dosimeter Readings • Never remove internal dosimeter elements from the protective plastic dosimeter case. • Store dosimeters away from sources of ionizing radiation when not in use. • Do not expose dosimeters to non-occupational radiation, such as medical or dental x-rays.
State and Federal regulations set maximum permissible yearly radiation dose (MPD) limits for adults. Exposure up to dose limits is not expected to cause adverse health effects. Maximum Permissible Dose Limits (MPD)
As Low As is Reasonably Achievable (ALARA) • ALARA is an Iowa Department of Public Health regulation set to minimize occupational radiation doses and to prevent personnel from exceeding regulatory maximum permissible dose limits. • Due to the limited use of radioactive materials at UNI, it is highly unlikely that a worker would be exposed to a dose above the maximum limit.
Why Practice ALARA? • Any type of ionizing radiation poses some risk. As exposure increases, so does risk. • Research shows that some people’s DNA is more resistant or susceptible to damage, and some people have an increased risk of cancer after exposure to ionizing radiation. • Limit your exposure whenever possible. Try to: • Minimize the time exposed • Maximize the distance from exposure • Use proper shielding
Radiation Badges • In any work associated with radiation that could result in exposure above 10% of the limit, users should wear a radiation badge. • Badges are designed to be worn to measure an individuals’ exposure on a one or two-month cycle. • If lead aprons are worn, badges should be clipped to the shirt collar.
Three Effective Strategies -Time- • Minimize the time and you will minimize the dose. • Pre-plan the experiment/procedure to minimize exposure time.
Three Effective Strategies -Distance- • Doubling the distance from the source can reduce your exposure intensity by 25%. • Use forceps, tongs, and trays to increase your distance from the radiation source. • Move the item being worked on away from the radiation area if possible. • Know the radiation intensity where you perform most of your work, and move to lower dose areas during work delays.
Three Effective Strategies -Shielding- • Position shielding between yourself and the source of radiation at all permissible times. Take advantage of permanent shielding (i.e. equipment or existing structures). • Select appropriate shielding material during the planning stages of the experiment/procedure. • Plexiglas, plywood and lead are effective in shielding radiation exposure. Use the proper shielding for the type of radioactive material present. • Acquiring proper shielding may involve complex calculations to configure energy and frequency emissions, size of the room, and environmental factors.
Three Effective Strategies -Shielding-(continued) • Be aware of the limitations of shielding. • Placing radioactive materials closer to the shield maximizes the protected area. • Effective shielding provides protection in all directions. Unshielded Area Shielded Area *Note: Moving the source of radiation further away from the shield will decrease the shielded area, thus the protected area will decrease.
Radiation Safety-Laboratory Rules- 1. Smoking, eating, and drinking are not permitted in radionuclide laboratories. 2. Food and food containers are not permitted in the laboratory. - Do not use refrigerators for common storage of food and radioactive materials. - Do not heat food or beverages in microwaves used to conduct research. - Food used only for research purposes and labeled “not for human consumption” is permitted.
Radiation Safety-Laboratory Rules- 3. Radionuclide work areas shall be clearly designated and should be isolated from the rest of the laboratory. The work area shall be within a hood if the radioactive material to be used is in a highly volatile form. 4. All work surfaces shall be covered with absorbent paper which should be changed regularly to prevent the buildup of contamination. 5. Work involving relatively large volumes or activities of liquid radioactive material should be performed in a spill tray lined with absorbent paper.
Radiation Safety-Laboratory Rules- 6. Protective clothing shall be worn when working with radioactive materials. This includes laboratory coats, gloves, and safety glasses. 7. Dosimeters shall be worn when working with relatively large quantities of radionuclides which emit penetrating radiation. 8. Mouth pipetting shall not be permitted in radionuclide laboratories.
Radiation Safety-Laboratory Rules- 9. All containers of radioactive materials and items suspected or known to be contaminated shall be properly labeled with tape or tagged with the radiation logo and the word “RADIOACTIVE”. 10. All contaminated waste items shall be placed in a container specifically designed for radioactive waste. Sharp items such as needles or razor blades shall be placed in a cardboard box, glass bottle, or sharps container.
Radiation Safety-Laboratory Rules- 11. A radiation survey shall be performed by the radionuclide user at the end of each procedure involving radioactive materials. All items found to be contaminated shall be placed either in the radioactive waste container or an appropriately designated area. Any surfaces found to be contaminated shall be labeled and decontaminated as soon as possible. The RSO shall be notified immediately if extensive contamination is found within the laboratory. 12. A record of the types and quantities of radionuclides possessed by each principal investigator at a given time shall be maintained.
-Laboratory Rules--Personal Protective Equipment- Always wear the proper PPE required when working with radiation and other hazardous materials. Proper PPE includes: • Safety glasses with side shields at all times while in the lab • Chemical splash goggles if liquids might splash or create aerosols • Especially important if wearing contact lenses to prevent material from getting under the lenses • Chemically resistant gloves recommended by the manufacturer for the material being used - do not use latex